public class 面向对象_3_学生实例与圆 {
    String name;
    int age;
    String sex;

    public void showAge(){
        System.out.println(age);
    }

    public int addAge(int i){

        int a = age+i;
        return a;
    }



    public void jiSuan(int r){
        System.out.println("圆的面积"+r*r*3.14);
    }





    public static void main(String[] args) {
        面向对象_3_学生实例与圆 xs =  new 面向对象_3_学生实例与圆();
        xs.age = 18;
        xs.showAge();
        System.out.println(xs.addAge(2));
        System.out.println(xs.addAge(2));

        xs.jiSuan(3);


    }


}
